Modern commercial aircraft make extensive use of computer systems to control aircraft behavior, plan and execute flights, and manage a myriad of other aircraft operations. Most current commercial transport aircraft include a flight management computer (FMC) that tracks flight segments or “legs” en route and can automatically control the aircraft to fly some or all of the segments. A control and display unit (CDU) or similar device provides input to and output from the FMC. Accordingly, pilots can load a series of flight segments into the FMC before a flight, monitor the progress of the flight by reference to the CDU, and/or modify the segments by entering new information via the CDU.
FIG. 1 illustrates a CDU 30 configured in accordance with the prior art and available on a variety of Boeing aircraft. The CDU 30 can include a display screen 31 and associated hardware input keys, including select keys 50 (shown as line select keys 50a and menu select keys 50b) and alphanumeric keys forming a keyboard 21. The display screen 31 includes a plurality of user update fields 33 that are updated by the aircraft operator or initially populated by the FMC, and system update fields 32 that are automatically updated by the FMC based on information received at the user update fields 33. For example, the operator can enter way point identifiers at the user update fields 33. The system can provide direction identifiers and distances between way points, based on the information received at the user update fields 33.
To operate the CDU 30, the operator presses one of the menu select keys 50b to determine which page dataset or menu is presented at the display screen 31. The operator then presses one of the line select keys 50a to select the user update field 33 that will be updated via data that are displayed at a scratch pad 35. If no data are present at the scratch pad 35, then the data in the selected user update field 33 are displayed at the scratch pad 35. The operator next edits information via the keyboard 21 while viewing the information at the scratch pad 35. Alternatively, the operator can enter information presented at the scratch pad 35 without first pressing one of the line select keys 50a. In either case, after the operator reviews the entered information for accuracy, he or she can depress the corresponding line select key 50a to load the information from the scratch pad 35 into the corresponding user update field 33. This information then becomes part of the aircraft flight plan.
One drawback with the arrangement described above with reference to FIG. 1 is that a change to the layout of the hardware input keys or the text identifier on the input keys can significantly increase the cost of upgrading the CDU 30. For example, because the input keys are fixedly positioned at the CDU 30, it can be prohibitively expensive and/or logistically difficult to change the layout of the CDU, for example, to change the size of the display screen 31, the location of the line select keys, or other aspects of the design of the CDU 30. Accordingly, airlines and other aircraft owners may be discouraged from installing system updates that can significantly ease pilot workload and improve the efficiency with which pilots operate their aircraft. As a result, aircraft owners may wait for a substantial period of time before implementing upgrades, and when they do so, they may incur considerable expenses.